Power-off Sequence Control for Electronic Devices
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Solution Overview
Problem
Microcontrollers face challenges in completing power-off sequences when power sources are suddenly lost, leading to potential system abnormalities during rebooting, as they require a power source to execute firmware control and may not finish processing before power is cut off.
Innovation Solution
An electronic device configuration that includes a battery, power circuit, microcontroller, and additional circuits (NAND and AND gates) to execute power-off sequences using both software and hardware flow control, ensuring successful power-off completion even when both AC and battery power are unavailable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If firmware control by microcontroller is used to implement power sequence specification, then power sequence control precision and abnormality detection capability are improved, but system reliability deteriorates when power sources are suddenly lost because the microcontroller cannot complete predetermined processing
Solution Approach 1:
The power-off sequence control is divided into two independent parts: (1) firmware control by microcontroller for normal operation, and (2) hardware circuit control (using NAND gate and AND gate) for sudden power loss scenarios. This segmentation allows each part to optimize for its specific function without compromising the other.
Solution Approach 2:
Hardware circuits (NAND gate and AND gate) are introduced as intermediaries between the microcontroller and the power-off sequence execution. These hardware circuits can independently execute the power-off sequence when the microcontroller fails due to sudden power loss, acting as a backup mechanism.
2Measurement precision
If microcontroller executes firmware control for power sequence, then power sequence specification is precisely implemented, but power-off completion time increases from nanoseconds to milliseconds
Solution Approach 1:
The firmware-based software control system is replaced with a hardware circuit-based system for power-off sequence execution. The hardware circuits (NAND gate and AND gate) can execute the power-off sequence in nanoseconds without the overhead of firmware interpretation and processing, dramatically reducing completion time.
Solution Approach 2:
The hardware circuits are pre-configured with the power-off sequence logic before power loss occurs. When sudden power loss happens, the pre-configured hardware circuits immediately execute the power-off sequence without requiring any processing or interpretation, enabling ultra-fast response.
3Reliability
If hardware circuits (NAND gate and AND gate) are added to execute power-off sequence, then system reliability during sudden power loss is improved, but device complexity increases
Solution Approach 1:
The critical power-off sequence execution function is extracted from the complex firmware control system and implemented in simple, dedicated hardware circuits. This extraction creates a minimal, reliable subsystem that handles only the essential power-off function, reducing overall system complexity for this specific task.
Solution Approach 2:
The hardware circuits (NAND gate and AND gate) are designed to autonomously execute the power-off sequence without requiring microcontroller intervention or complex control logic. The circuits self-manage the power-off process by directly responding to power loss conditions, eliminating the need for complex coordination mechanisms.
Data Source
AI summary
According to one embodiment, an electronic device is configured to power a component in the electronic device by using power from an AC power device or the battery. The electronic device is configured to output a first signal indicative of whether the power circuit is capable of powering the component. The electronic device is configured to output a second signal indicative of whether at least either of the AC power device or the battery is capable of supplying power used by the power circuit. The electronic device is configured to change a polarity of a third signal for notifying whether the component can be powered based on a polarity of the first signal and the second signal.